Musical instrument



Nov. 12, 1940. J. A. KOEHL 2,221,097

MUSICAL INSTRUMENT Filed May 24, 1940 2 Sheets-Sheet 1 Nov. 12, 1940. J. A. KOEHL 2,221,097

MUSICAL INSTRUMENT Filed May 24, 1940 2 Sheets-Sheet 2 Will Me n $2 6%; 1E? Ra w aAfia wanna Fan 6% G'zAz 20s aL'aIZaGalAa 301 Patented Nov. 12, 1940 PATENT OFFICE 2,221,091 MUSICAL INSTRUMENT James A. Koch], Chicago, Ill., assignor to Central Commercial Company, Chicago, 1111, a corporation of Illinois Application May 24, 1940, Serial No. 336,929

12 Claims.

This invention relates to musical instruments of the type employing playing-keys associated with different notes of a musical scale and has for its general object, the provision of means enabling faithful reproduction of sounds characteristic of various musical instruments and particularly, but not necessarily, sounds characteristic of percussive instruments.

While I have disclosed herein a preferred embodiment of my invention in which photographic sound recordings are converted into undulating potential, thence into sound energy of corresponding waveform,.the gist of my invention re- I sides in the provision of a sound record of any well known form, and means including reproducing mechanism for automatically maintaining the front or starting end of a sound track substantially in a starting position relative to an electrical pick-up device when an associated playing-key is elevated and for automatically moving the record in a reproducing direction when the key is depressed and similarly returning the record to said starting position when pressure is removed from the key.

The main objects of my invention are as follows:

(1) To provide an organization of mutually coacting instrumentalities primarily designed, faithfully to simulate the tones of percussive instrument such as chimes, bells or other resonators, vibrating devices, sounders or the like which are attuned to each other in diatonic succession.

(2) To provide key-controlled mechanism for electrically producing percussive sound effects with absolute fidelity, i. e. if the instrument being simulated is a bell or similar vibrating body in which there are no points of absolute rest, the fundamental note of the bell and all harmonic partials periodically generated by the bells vibrating segments, will be audible and will grow and decay at a rate which is exactly characteristic of a bell when it is struck with a hammer.

(3) To provide key-operated mechanism which electrically controls conduction to an electrical sound producer of undulating potential of any desired pitch and in absolute synchronism with motion in a reproducing direction of a sound record relative to an associated pick-up device and which automatically renders the pick-up device inactive when the record is moving in an opposite direction.

(4) To provide mechanism in which the actions 5 of its parts are timed so that the first end of the sound track of a sound record which is disposed out of the effective field of a pick-up device when a key is elevated, will be correctly correlated with said pick-up device the moment the record has attained a predetermined reproducing speed, thus 5 insuring that the fundamental tone of the recorded instrument and all the harmonics of said fundamental tone will be sounded in an order exactly characteristic of the recorded instrument and at the pitch of a particular musical note. 10

(5) To provide record moving mechanism which is common to and by means of which any desired number of sound records can be simultaneously moved at reproducing speeds upon actuation of a like number of playing-keys.

(6) To provide means for moving the records in a reproducing direction, each at a speed which is predetermined relative to the speed at which recordings are made upon the record.

(7) To provide mechanism enabling the same 20 note to be sounded in relatively rapid succession.

(8) To provide an organization of instrumentalities which is compact, simple of construction, inexpensive as compared with the actual cost of an instrument, the tones of which are desired to 5 be simulated, positive in action and capable of being used either as a portable, light weight instrument, complete in itself, or as an accessory to any musical instrument such as a pipe organ, 30 electric organ, piano, or the like.

(9) To provide an organization of the character specified in which a rectilinear record of short length functions in coaction with winding and unwinding mechanism to insure repetitous sounding of the same note substantially with the speed typical of the instrument being simulated.

(10) To provide an instrument enabling faithful reproduction of the tones of a pipe organ both as to the quality of a particular instrument and the rate of growth of the tones.

(11) To provide means for automatically stopping motion of a record in a reproducing direction in the event that a key is held depressed longer than necessary for the full sounding of anote.

(12) To provide means for resetting the motion stopping means from the console of the instrument, the said means being common to all records embodied in the instrument.

My invention will be more clearly understood from the specification hereinafter following and by reference to the accompanying drawings, in which:

Figure 1 is a diagrammatic view of a recording circuit and means therein for making the photographic solmd records employed in my improved instrument:

l igurezisadiagrammaticillustrationoitbe reproducing system ior converting sound recordlngs into pulsating potentials and ior reconverting said potentials into sound energy oi the same waveiorm as the recorded sound;

FigureSisadiagrammaticillustrationoithe shutter and motion controlling magnet circuits;

in Flgurei is aviewpartlyin section andpartly in elevation oi the mechanism ior moving a record at a reproducing speed relative to a reproducing system;

Figure 5 is a view'in elevation oi the shutter 16 control mechanism;

Figure 6 is a detail view in elevation oi the continuously operating, constant speed 'shait having a common set oi loose record winding spools:

Figure 'l is a view in plan oi a typical keyboard 20 embodying a key ior each record employed in the instrument, and

Figure 8 is a diagrammatic view oi a modified iorm oi automatic control circuit ior each record and means for resetting same irom the console oi 2 the instrument.

In order that persons trained in the art to which my invention relates may understand and practice my invention, I have shown in the present embodiment oi the invention a short key board 8 consisting oi white keys ranging irom G: to A4 and black keys, ranging irom G#s to can, providing a practical range oi chime tones. It instruments such as the vibra-harp, glockenspiel, Xylophone, piano, string harp. drum. etc. are de- 36 sired to be simulated, the number of octaves will, oi course, be correspondingly increased. As the main invention has broadly to do with means by which any desired percussive tone can be iaithiully simulated, the particular type oi instrument 40 to be simulated and the number oi pitches per manual employed, is at course immaterial, and nothing herein shown or described shall be considered as limiting in this respect.

While I have elected to employ a photo-electric cell or similar light sensitive device as a pickup in association with a photographic sound record, having recorded thereon a musical note oi predetermined pitch to be converted into undulatlng potential oi corresponding wave iorm by said pick-up device, it shall be understood that any other well known means may be substituted thereior without departing irom the spirit and intention oi my invention. One such means may consist oi a metal tape having magnetically recorded sound thereon which may be magnetically converted into undulating potential when the tape is moved in the pick-up presence of a pickup magnet.

In Figure l, a photographic film l is continuously moved across the lens I at a predetermined recording speed, and the light irom a lamp I is recorded on the film in the form oi a minute ray obtained through a pin point aperture or iocused to a point by a lens in a manner well known in the art. The lamp is controlled by and in accordance with sound waves generated in the pick-up transmitter or microphone circuit which includes a transmitter or microphone t in a closed circuit with a source oi current 9, the

lamp circuit and the microphone circuit being inductively coupled to each other through transiormer coils ll. Ii a vibratory body is set in motion in the pick-up vicinity oi the microphone I, sound waves thereby generated will set up rs pulsating current in the microphone and thereby operate theclosed circuitoithelampLandcause light variations which ly control variation in intensity of light supplied to the recording-speed between a light sensitive electrical device II and a source oi light Ii oi conla stant intensity. Light passing through the film' willvaryinaccordance withthe exposure oithe film l and pulsating currents produced by said device ii and varying directly in accordance with the originalsoundwaveswillbeimpressedupon II the input circuit oi an ampliiying system It and the amplified currents converted back into sound waves by an electrical sound producer ll connected in the output circuit oi said system.

The light source I! is cut oil irom the photo- Q electric cell Ii by a key-operated shutter II, the operation oi which will be explained presently.

Thefilmlshowninl'igureziswoundupon a rotatable spool It and held in a wound condition when an associated plums-key is elevated. 18 For this purpose, a winding spring ii i em loyed andhasoneendfixedtothcspoolanditsother end attached to a suitable fixed point, (not shown). The vertical or rectilinear stretch oi the film passes through an p rture gate II at so the light source it, and as shown, the small light slit It in said gate is closed by the aiorementioned shutter II. A slight movement oi the shutter on its pivot, such as will be erected by a magnet II when energised. will move the shutter I against the action oi a spring 2i and away irom a stop at to thereby uncover said aperture as long as the key is depressed.

Theoppositeendoithefilmisfixcdtothelarge diameter hub oi a take-up spool 22, loosely mount-' ed upon a shait II which continuously operates at an assigned reproducing speed. 'Ihe spool 22 bass clutchiace Ilstoneside,the oppositeside oithespoolbeinginireerunningengagement withafiatdisc2l.fisedtosaidshait.

Splined to the shaft it to slide thereon relative to the clutch iace ll oi the spool 22, is a clutch I". A iork IO, pivoted at II and provided with an armature carrying arm is connected with saidclutch,ssshown. amagnettlisassocisted g. withssidarmllandwhenenergisedaswhen depressing a playing-key, attracts the arm and moves the iork against the action oi a clutch releasing spring ll. In this manner, the clutch 211 is engaged with the iace It oi said spool, lg thereby causing the spool to rotate with the shaft Ilsoastomovethefilmacrouthelightsource and against the tension oi the spring ll oi the spool II.

In Figure 2, x denotes the first or starting end Q or the sound track on the film I, it being noted, that its position is above the source l2, a distance calculated to enable the film to attain its necessary reproducing motion when the starting end oi its sound track shall have arrived at the light gg source.

'ihe magnets II and it are connected in the respective parallel circuits shown in Figure 3. and the playing-key which is common to said magnets has a contact device 82 which is close circuited to with a contact device 88 which connects to one pole oi a source oi current for energizing said magnets when the key is depressed. In this manner, the shutter II is opened so as to xpose the device II to the light source I! simultane- 1g ously with starting the record in motion in a reproducing direction.

When both magnets are simultaneously deenergized, the shutter returns to its closed position and the illm is rapidly rewound upon spool II.

In order that a small length of film can be used, the record is made upon a him at a slow recording speed which will be the same as the reproducing speed of shaft II. To make this further possible and thus allow any key to be succes:.ively depressed at desired intervals, the diameters of the hubs of both spools I. and 22 can be large as compared with the overall length of the film.

The shaft 23 is common to any desired number of pairs of spools II and 22 and as the operation of each pair of spools is the same and controlled by an associated playing-key, it is thought that the description, detailed as to a single pair of said spools will sufllce for the entire set of such pairs of spools. While the shaft 23 is common to said entire set of pairs of said spools, it may also be the source of driving energy for any desired number of said sets as would be desirable when a single instrument is equipped with a plurality of keyboards. The shaft may be driven by means of any well known constant speed motor and is preferably provided with a suitable inertia mass I00.

Any desired number of keyboards can be employed according to the number of different instruments desired to be simulated.

While the invention is particularly useful for the simulation of the qualities of different percussive instruments, it is understood that I am not to be limited in this respect. Pipe tones can be recorded on film in the manner aforementioned and while the tones cannot be sustained indefinitely, desired musical results can never the less be attained in a highly satisfactory manner.

While I show a light source individual to a single light sensitive device, it is understood that in practice, a light source common to any desired number of light sensitive devices can be employed without departing from the spirit and intention of my invention.

In the modified form of my invention shown in Figure 8, a normally close clrculted switch 35 is connected in the circuit lead 36 from contact device 33, and has a tall 36 provided with a slot 31 through which an associated record is threaded. The record has a lug 38 which is disposed at the end of its sound track and adapted to engage said tail of the switch and move the latter in a direction to break the circuit and simultaneously cause deenergization of both magnets 20 and 30. This stops further motion of the record and causes the latter to be rewound upon the spool It. When the switch reaches its opened position, the tip thereof is disposed in close proximity to a resetting lever IS. The lever has a control connection ll which runs to the console of the instrument and is disposed preferably above an associated key of the instrument. Thus it follows that when a circuit is automatically broken in any instance where the finger of the player is held against a key longer than required for a complete sounding of a note, it can quickly be closed by manipulation of the lever as aforestated.

When the bell sounds its deepest note, the coalescence of its pulses causes it to divide into four vibrating segments, separated from each other by four nodal lines which run up from the soundbow to the crown of the bell. The place where the hammer strikes is always the middle of a vibrating segment; the points diametrically opposite are also the middle of such segment. Ninety degrees from these points are also vibrating segments, while at 45 degrees right and left of them are the nodal lines. If a hammer falls on any one of said segments, the sound-bow passes periodically through certain changes, such, that at one moment, it is oval in one plane and at the next moment, it is oval in a plane at right angles to the long axis of the first oval. The changes from one oval to the other, constitute in fact the vibrations of the bell. The four points where the two ovals intersect each other, are the nodes. The number of vibrations executed by a bell in a given time, varies directly as the square of the thickness, and inversely as the bell's diameter. Beginning with the fundamental note, the number of vibrations corresponding to the respective divisions of a bell is as follows:

Number of divisions, 4, 6, 8, 10, 12 Numbers the squares of which express the rates of vibration, 2, 3, 4, 5, 6

Thus if the vibrations of the fundamental tone be 40, that of the next higher tone will be 90, the next, 160, the next 250, the next 360, and so on.

To the best of my knowledge it has never before been possible faithfully to simulate either the tones of a bell or the tones of other similar vibratile bodies by admixtures of various partials synthetically produced as by means of various well known frequency producing devices. By reason of the fact that my invention employs a sound record of the actual instrument being simulated and that the first or starting end of the record's sound track is always in a starting position when a playing-key is elevated, it follows that not only are the vibrations of the instrument correctly produced, but that, in addition thereto, the rate at which each partial speaks upon and following the blow of the hammer, will be absolutely in accordance with the actual rate of growth and decay of the tones of the bell.

It is of course understood that for each spool 22, there will be one spool it which is individual thereto and that the operation of said spool It will be wholly independent of any other spool l6 of the set employed.

What I claim as my invention is:

1. The combination with a plurality of idle,

movably supported devices respectively controlling production of currents of varying potential, each current of varying potential having the waveform characteristics of a fundamental musical tone and harmonics of said tone; means in coaction with said devices for producing said currents of varying potential during constant motion of said devices; means for urging said devices to idle positions and in starting relation to said current producing means so that when placing said devices in motion the waveforms of currents of varying potential are each thereof sequentially produced in the natural order of the sounding of a fundamental tone and the harmonics of said tone; and means for placing any of said devices in operation to effect production of selected waveforms of current of varying potential and including a selector for each individual one of said devices connected with said means to move'said device against the tendency of a respective urging means.

2. In a musical instrument, mechanism and a plurality of idle, movably supported sound reca film gate disposed between said source of light and the light sensitive device and provided with a shutter for intercepting a. beam of light from said light source and preventing projection thereof upon said light sensitive device, means for normally closing the shutter, a photographically obtained sound record associated with said gate and adapted when moved at constant speed and the shutter is opened to control actuation of said light sensitive device, means for respectively moving the record in two directions, an electric circuit, a key connected in said circuit for controlling same, and magnetically actuated devices said light sensitive device when releasing said 10 key.

JAMES A. KOEHL. 

